Giro Xen MTB Helmet - Performance Exclusive In-Mold construction reinforces the area around the vents and ribs, creating a one-piece exoskeleton, which allows the helmet to be lighter, more durable and better ventilated than traditional designs EPS liner and polycarbonate shell add reinforcement in crucial areas 17 Wind Tunnel vents with internal channels thrust cool, fresh air over and around your head while forcing heat and stale air out P.O.V. visor allows 15 of tool-free, on-the-fly vertical adjustment while preventing the visor from rattling and coming loose over rough and technical terrain Roc Loc 4 retention system offers full adjustment of both fit tension and vertical position, making it easy to customize the fit for more stability